ART: Fix ArenaStack::AllocWithMemoryTool().

MEMORY_TOOL_MAKE_NOACCESS() takes the size of the address
range as the second argument, not the end the range.

Bug: 27156726
Change-Id: I05c8224a1d3c619919b203f407fb770c7c49cc9f
diff --git a/runtime/base/scoped_arena_allocator.cc b/runtime/base/scoped_arena_allocator.cc
index 90c6ee3..7d04fa0 100644
--- a/runtime/base/scoped_arena_allocator.cc
+++ b/runtime/base/scoped_arena_allocator.cc
@@ -99,7 +99,7 @@
   if (UNLIKELY(static_cast<size_t>(top_end_ - ptr) < rounded_bytes)) {
     ptr = AllocateFromNextArena(rounded_bytes);
     CHECK(ptr != nullptr) << "Failed to allocate memory";
-    MEMORY_TOOL_MAKE_NOACCESS(ptr, top_end_);
+    MEMORY_TOOL_MAKE_NOACCESS(ptr, top_end_ - ptr);
   }
   CurrentStats()->RecordAlloc(bytes, kind);
   top_ptr_ = ptr + rounded_bytes;